Gardening with artificial lights adds a new dimension to growing plants indoors. you can grow plants anywhere you want, not just near natural light sources, and you can use otherwise unusable spaces. Gardening with artificial lights also offers consistency -  plants don't have to adjust to drastic changes or varying levels of light.  In Minnesota, the light intensity in winter is about 1/10th the intensity in summer.  Plants struggle to survive the low light levels, so they are more susceptible to insect and disease problems.  Providing additional light indoors doesn't have to be difficult or expensive. Give it a try. The improved performance of your plants will amaze you!

How do I know if my plants need artificial light? It is difficult to judge just how much natural light you have available. When you know what to watch for, your plants will tell you. If they aren't getting enough light, plants tend to grow taller and weaker, and the leaves will be lighter in color. They won't have as much foliage and new leaves might be larger. Sometimes, the inner or lower leaves will yellow.  The plants will lean toward the light there is.

Won't my plants get enough light in a sunny window? Several factors reduce the intensity of light indoors, including distance from the source and shadows cast from other plants. The angle of the sun and the strength of the light change from week to week, and some plants need much more light than others.

Are there different types of light fixtures? You can use standard lamps, spotlights, under-cabinet lights, shop lights or plant light fixtures. Just make sure they are rated for the wattage you will be using. If you are in doubt, all new fixtures are rated and should say on the package what type of bulbs can be used and the wattage. In addition to individual lights, light units can be purchased or constructed.

What types of light bulbs are available? The most common lights used for plants in the home are fluorescent and incandescent. There are more intense forms of light available (such as halogen, sodium and metal halide) but they require specialized fixtures and are too large for most homes.

Which type of light is best? Fluorescents provide good light, are the least expensive to burn and produce the least heat. Unfortunately, full spectrum tubes can be expensive to purchase. Incandescent lights are the least expensive to purchase and provide good light. But they are costly to run and produce lots of heat, so they can't be placed close to the plants. From the perspective of the plants, fluorescents are the best for home use. Keep in mind that plants prefer their light source to come from above. Lights aimed up from below make a dramatic display, but the light is not actually useful to the plants.

Should I use regular light bulbs or do I need special plant bulbs? It depends on what you are growing.  Plants do well with special grow bulbs that provide all the spectrum of light they need for good growth and blooming. But if you aren't growing blooming plants, full spectrum lights aren't really necessary. The light provided by regular fluorescents is fine for foliage plants. Research shows a combination of one cool and one warm fluorescent works as well as any plant light. You can usually purchase 48" cool white bulbs for $2 or less and a warm white for $4 or less. You can always add a small fixture with a grow bulb to encourage some blooming. Now there are fluorescent bulbs available that fit into a standard incandescent light fixture (they cost $8-12 each). They can be used as spotlights, providing inexpensive cool light.

How much light do my plants need? This will vary according to the specific plants,
but there are some guidelines. Trial and error will tell you if you should adjust the amount of light you provide. The closer your plants are to the light source, the more light they will gather.  Most plants need a minimum of 12 hours of light each day. This light can be all artificial or you can use artificial lights to supplement natural light. Plants that need high light may require up to 16 hours of light each day. 

How do I know how many lights I need? A general rule is: for every square foot of plant, you should provide 15-20 watts of light. Your best bet is to monitor how your plant is responding. It will tell you if it needs more light.

Are there some more specific recommendations on how much area lights will cover?
Two 48" 40 watt fluorescent bulbs in a fixture with a reflector will adequately light a 2' by 4' area when mounted 24-30" above the table or floor. Four 48" 40 watt fluorescents are better for most germinating and early growth stages and will light a 3' by 4' area. The smaller 20 watt tubes are best for confined areas such as terrariums. A 100 watt spotlight will provide adequate light to a 2' by 2' area if mounted within a foot of the plants.

Can I put my plants too close to the lights? Only if you are using lights that produce heat (like regular incandescent bulbs). You can position your plants within a few inches of fluorescent bulbs to take full advantage of their output. It really is amazing how much more light is available by simply moving the plants several inches closer to the light.

Can plants have too much light? It is almost impossible to provide too much light, but plants do need a regular period of darkness each day. It's easy to use an inexpensive timer that will turn your lights on in the morning and off in the late evening. (or vice versa)

Is there anything else I can do to make better use of my lights? First of all, reflectors on your fixtures will put most of the light where it is needed. Next, have walls near the plants painted white or a light color, or consider covering them with a reflective material such as silver mylar or aluminum foil. Finally, dust your light bulbs and your plants occasionally. Dust makes a significant difference in plants' ability to breath and absorb light.

Additional Bachman's Information
Indoor Plants for Various Light         
Caring for Plants While You're Gone
Moving Plants In and Out               
Signs of Trouble with Indoor Plants
Watering Basics for Indoor Plants

Recommended Products
GE Show and Gro Lights
Incandescent and Fluorescent Bulbs
Quality Plants, Containers,Saucers
Bachman's Exceloam Potting Soil
Bachman's Excel Gro™ Water Soluble Plant Foods

©Bachman's 2008